1. Field of the Invention
The invention generally relates to battery operated surgical powered instruments. More particularly, the invention relates to battery packs which enable the use of non-sterile rechargeable batteries with sterile surgical instruments.
2. Description of the Prior Art
In order to enable the use of rechargeable non-sterile batteries in sterile surgical instruments, users employ a known “sterile transfer” technique. While possibly known by other names, this technique generally entails the sterilization and use of a sterile battery container to be attached to a sterile powered instrument. The sterilized container is held in a sterile field (by a scrub nurse, for example) and is shielded by a sterile shroud. A non-sterile, charged battery (held by a circulating nurse, for example) is placed into the sterilized container with care so as not to contaminate the already sterilized container. The shroud is then removed by the circulating nurse and the sterilized container is closed by the scrub nurse and attached to the instrument. The container hermetically encloses the battery and has its own exterior terminals which are connected to the battery terminals and through which the instrument is powered.
The battery used in a sterile transfer container is generally a battery pack comprising a plurality of individual battery cells wired and bound together in one unit. The terminals of the cells are connected in series and to the terminals of the battery pack. As used herein, the term “battery” will be understood to include a battery pack.
Prior art battery packs generally have terminal contacts which are surface mounted and engageable by contiguous engagement with another surface contact in the device with which the battery pack is designed to operate. The surface contacts are designed to be pressed toward each other, essentially pushing in opposite directions along an imaginary line passing through both contacts at the point at which they are contiguous. Sometimes a spring force is designed into the engagement to enhance the force with which the terminal contacts press against the device contacts.
Surface contacts are subject to vibration in powered surgical instruments and this may increase wear and affect performance. Also, surface contacts may subject a battery to risk of shorting if the battery terminals inadvertently connect conductive materials before being put into the intended instrument.
Additionally, surface contacts necessarily increase the size of the battery and/or battery/instrument combination. This occurs simply because of the necessity of providing relatively massive contacts and/or spring mechanisms to maintain a secure connection during use.
Accordingly, it is an object of this invention to produce a battery pack with increased security from failure.
It is also an object of this invention to produce a battery pack having a reduced risk of shorting across its terminals.
It is an additional object of this invention to produce a battery pack which has a smaller height to minimize the size of the sterile transfer container or instrument into which the battery pack is designed to fit.